16 results on '"Vivaldi, Daniele"'
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2. The European GO-VIKING project on flow-induced vibrations: overview and current status.
- Author
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Papukchiev, Angel, Zwijsen, Kevin, Vivaldi, Daniele, Hadžić, Hidajet, Benhamadouche, Sofiane, Benguigui, William, and Planquart, Philippe
- Published
- 2024
- Full Text
- View/download PDF
3. Fluid-Structure Interaction Simulations of a Rod Subjected to a Water Axial Flow in a Nuclear Core Relevant Configuration
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Vivaldi, Daniele, additional and Pulicani, Roxan, additional
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- 2023
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4. A numerical model for the CO2–sodium chemical interactions in Sodium Fast nuclear Reactors
- Author
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Vivaldi, Daniele, Gruy, Frédéric, and Perrais, Christophe
- Published
- 2015
- Full Text
- View/download PDF
5. Flow-Induced Vibration Simulations of a Straight Tube Bundle in Water Cross-Flow, Through URANS Approach
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Vivaldi, Daniele, additional and Baccou, Jean, additional
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- 2022
- Full Text
- View/download PDF
6. Fluid-Structure Simulations of Vortex Shedding Induced Vibrations on Two In-Line Cylinders in Water Cross-Flow
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Vivaldi, Daniele, additional
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- 2022
- Full Text
- View/download PDF
7. Assessment of an Euler-Bernoulli Beam Model Coupled to CFD in Order to Perform Fluid-Structure Simulations
- Author
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Vivaldi, Daniele, additional and Ricciardi, Guillaume, additional
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- 2022
- Full Text
- View/download PDF
8. Modelling of a CO2-gas jet into liquid-sodium following a heat exchanger leakage scenario in Sodium Fast Reactors
- Author
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Vivaldi, Daniele, Gruy, Frédéric, Simon, Nicole, and Perrais, Christophe
- Published
- 2013
- Full Text
- View/download PDF
9. Optimizing Coupled Fluid-Structure Simulations for Nuclear-Relevant Geometries
- Author
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Vivaldi, Daniele and Ricciardi, Guillaume
- Abstract
The numerical simulation of fluid-structure interactions (FSI) has gained interest to study flow-induced vibrations. Nevertheless, the high computational resources required by such simulations can represent a significant limitation for their application to industrial configurations. Therefore, simplified modeling approaches, when physically applicable, can represent an interesting compromise. This can be the case of slender structures (tubes, rods) often encountered in nuclear power plants. In this paper, an Euler–Bernoulli beam finite element model is implemented inside the computational fluid dynamics (CFD) code code_Saturne. With the goal of finding CFD methods less expensive than large eddy simulations (LES), unsteady Reynolds Navier–Stokes (URANS) and hybrid URANS/LES approaches are considered. The resulting fluid-structure model is able to calculate the vibration response of cantilever beams under a fluid flow, avoiding the necessity of CFD-finite element method (FEM) code coupling. The first part of the paper describes the model and its implementation: it allows to perform 2-way explicit fluid-structure coupling, using the Arbitrary Lagrangian-Eulerian approach to account for the structure deformations. Validation test cases are presented in the second part: first, the model is validated in terms of frequency, added mass, and damping for a cylinder vibrating in static air and water; then, the model is validated toward the vortex-induced resonance and lock-in mechanisms for a cylinder subjected to water cross-flow. The model is then applied to a real experimental configuration of two in-line cylinders in water cross-flow: the calculated vibrations are found to be in good agreement with the experimental measurements.
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- 2024
- Full Text
- View/download PDF
10. Numerical modeling of two-phase underexpanded reactive CO2 into sodium jets in the frame of sodium nuclear fast reactors
- Author
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Vivaldi, Daniele, Gruy, Frédéric, Perrais, Christophe, Département Technologie Nucléaire (DTN), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Laboratoire Georges Friedel (LGF-ENSMSE), École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-Université de Lyon-Centre National de la Recherche Scientifique (CNRS), Département PROcédés Poudres, Interfaces, Cristallisation et Ecoulements (PROPICE-ENSMSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SPIN, Centre Sciences des Processus Industriels et Naturels (SPIN-ENSMSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT), CEA-DEN/DTN/SMTA/LIPC Cadarache, and Toucas, Andrée-Aimée
- Subjects
Sodium Fast Reactors ,Underexpanded two-phase jets ,[SPI.GPROC] Engineering Sciences [physics]/Chemical and Process Engineering ,Heterogeneous gas-liquid chemical reaction ,Supercritical CO2 cycles ,[SPI.GPROC]Engineering Sciences [physics]/Chemical and Process Engineering ,Multi-fluid CFD - Abstract
International audience; Supercritical CO2 (s CO2) Brayton cycles have gained interest in the frame of Sodium-cooled nuclear Fast Reactors (SFRs), as an alternative to the conventional water Rankine cycles. If CO2 leaks inside the CO2-Na heat exchanger, an underexpanded CO2-into-liquid-sodium jet is formed. CO2 leaks at sonic velocity and chemically reacts with sodium, through an exothermic reaction. The consequences of such a scenario must be investigated, in order to predict the temperature increasing inside the heat exchanger and on the tube walls, due to the exothermic chemical reaction, as well as the reaction products distribution inside the heat exchanger. This article presents a numerical approach for modeling such a two-phase reactive jet. A two-fluid multi-component CFD approach is employed, with a heterogeneous reaction between the CO2-gas and the sodium-liquid phases. The model allows to predict the most relevant information, such as temperature distribution, the jet penetration length and the reaction products distribution downstream the CO2 leakage. Some experimental studies on underexpanded gas-into-sodium reactive jets, available in literature, have been compared to our numerical results. It is found that the numerical temperature profiles are consistent with the ones experimentally measured.
- Published
- 2015
11. Modeling of underexpanded reactive CO2-into-sodium jets, in the frame of sodium fast reactors
- Author
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Vivaldi, Daniele, Département PROcédés Poudres, Interfaces, Cristallisation et Ecoulements (PROPICE-ENSMSE), École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SPIN, Laboratoire Georges Friedel (LGF-ENSMSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-Université de Lyon-Centre National de la Recherche Scientifique (CNRS), Ecole Nationale Supérieure des Mines de Saint-Etienne, and Frédéric Gruy
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Optic probe two-phase measurements ,Two-phase CFD ,[SPI.GPROC]Engineering Sciences [physics]/Chemical and Process Engineering ,Réaction chimique hétérogène ,Ecoulements diphasiques ,Multi-fluide numerical model ,Réacteurs nucléaires rapides sodium ,Jets diphasiques sous-détendus - Abstract
This PhD work was motivated by the investigations in the frame of supercritical CO2 Brayton cycles as possible energy conversion cycles for the Sodium-cooled Fast nuclear Reactors (SFRs). Following an accidental leakage inside the sodium-CO2 heat exchanger of a SFR, the CO2, having an operating pressure of about 200 bars, would be injected into the low-operatingpressure liquid sodium, creating an underexpanded reactive CO2-into-sodium jet. The goal of this PhD work is the development of a numerical model of the two-phase reactive CO2-into-sodium jet.A numerical model of an underexpanded non-reactive gas-into-liquid jet was developed, adopting a 3D unsteady multi-fluid CFD approach. The numerical results have been validated through the experimental results obtained with a facility employing optical probe technique. A numerical model for the chemical reaction between sodium and CO2 was then developed and integrated into the 3D two-fluid model. The resulting model allows to determine the temperature profiles inside the reactive jet and on the heat exchanger tubes.; Ce travail de thèse s’est inscrit dans le contexte d’utilisation d’un cycle de conversion de l’énergie de type Brayton au CO2 supercritique, pour les réacteurs à neutrons rapides refroidis au sodium (RNRNa). Dans le cas d’une fuite accidentelle dans l’échangeur de chaleur Na − CO2 d’un RNRNa, le CO2, avec une pression opérative d’environ 200 bars, serait injecté dans le sodium liquide qui se trouve à basse pression,provoquant un jet sous-détendu et réactif deCO2 dans le sodium. L’objectif principal de ce travail de thèse était le développement d’un modèle numérique du jet réactif diphasique de CO2 dans du sodium.Un modèle numérique d’un jet sous-détendu non-réactif de gaz dans du liquide, utilisant une approche3D non-stationnaire de type multi-fluide CFD, a été développé. Les résultats numériques ont été validés à travers la comparaison avec résultats expérimentaux obtenus avec mesures optiques. Un modèle décrivant la réaction chimique entre le sodium et le CO2 a été ensuite développé et intégré dans le modèle 3D multi-fluide. Le modèle résultant permet de calculer les profils de température obtenus au sein du jet et sur les parois des tubes de l’échangeur de chaleur.
- Published
- 2013
12. Modélisation de jets réactifs et sous-détendus de CO2 dans le sodium, dans le contexte des Réacteurs à neutron rapides refroidis au sodium
- Author
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Vivaldi, Daniele, Département PROcédés Poudres, Interfaces, Cristallisation et Ecoulements (PROPICE-ENSMSE), École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SPIN, Laboratoire Georges Friedel (LGF-ENSMSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-Université de Lyon-Centre National de la Recherche Scientifique (CNRS), Ecole Nationale Supérieure des Mines de Saint-Etienne, and Frédéric Gruy
- Subjects
Optic probe two-phase measurements ,Two-phase CFD ,[SPI.GPROC]Engineering Sciences [physics]/Chemical and Process Engineering ,Réaction chimique hétérogène ,Ecoulements diphasiques ,Multi-fluide numerical model ,Réacteurs nucléaires rapides sodium ,Jets diphasiques sous-détendus - Abstract
This PhD work was motivated by the investigations in the frame of supercritical CO2 Brayton cycles as possible energy conversion cycles for the Sodium-cooled Fast nuclear Reactors (SFRs). Following an accidental leakage inside the sodium-CO2 heat exchanger of a SFR, the CO2, having an operating pressure of about 200 bars, would be injected into the low-operatingpressure liquid sodium, creating an underexpanded reactive CO2-into-sodium jet. The goal of this PhD work is the development of a numerical model of the two-phase reactive CO2-into-sodium jet.A numerical model of an underexpanded non-reactive gas-into-liquid jet was developed, adopting a 3D unsteady multi-fluid CFD approach. The numerical results have been validated through the experimental results obtained with a facility employing optical probe technique. A numerical model for the chemical reaction between sodium and CO2 was then developed and integrated into the 3D two-fluid model. The resulting model allows to determine the temperature profiles inside the reactive jet and on the heat exchanger tubes.; Ce travail de thèse s’est inscrit dans le contexte d’utilisation d’un cycle de conversion de l’énergie de type Brayton au CO2 supercritique, pour les réacteurs à neutrons rapides refroidis au sodium (RNRNa). Dans le cas d’une fuite accidentelle dans l’échangeur de chaleur Na − CO2 d’un RNRNa, le CO2, avec une pression opérative d’environ 200 bars, serait injecté dans le sodium liquide qui se trouve à basse pression,provoquant un jet sous-détendu et réactif deCO2 dans le sodium. L’objectif principal de ce travail de thèse était le développement d’un modèle numérique du jet réactif diphasique de CO2 dans du sodium.Un modèle numérique d’un jet sous-détendu non-réactif de gaz dans du liquide, utilisant une approche3D non-stationnaire de type multi-fluide CFD, a été développé. Les résultats numériques ont été validés à travers la comparaison avec résultats expérimentaux obtenus avec mesures optiques. Un modèle décrivant la réaction chimique entre le sodium et le CO2 a été ensuite développé et intégré dans le modèle 3D multi-fluide. Le modèle résultant permet de calculer les profils de température obtenus au sein du jet et sur les parois des tubes de l’échangeur de chaleur.
- Published
- 2013
13. Experimental studies and two-fluid numerical approach for underexpanded CO2-Gas jet into liquid-sodium
- Author
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Vivaldi, Daniele, Gruy, Frédéric, Simon, Nicole, Département Technologie Nucléaire (DTN), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Centre Sciences des Processus Industriels et Naturels (SPIN-ENSMSE), École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT), Département PROcédés Poudres, Interfaces, Cristallisation et Ecoulements (PROPICE-ENSMSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SPIN, Laboratoire Georges Friedel (LGF-ENSMSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-Université de Lyon-Centre National de la Recherche Scientifique (CNRS), Alessandro Petruzzi, CEA DEN/DTN/STPA/LIPC Cadarache, and Toucas, Andrée-Aimée
- Subjects
Physics::Fluid Dynamics ,generation IV nuclear power reactors ,SFR ,Sodium-cooled Fast Reactor ,[SPI.GPROC] Engineering Sciences [physics]/Chemical and Process Engineering ,supercritical CO2 ,[SPI.GPROC]Engineering Sciences [physics]/Chemical and Process Engineering ,interfacial friction model - Abstract
International audience; Sodium-cooled Fast Reactors (SFRs) represent one of the most promising technologies in the context of generation IV nuclear power reactors. In order to improve electric efficiency and to avoid a reaction between Sodium and water when Rankine cycles are used, the concept of Brayton cycles using supercritical CO2 is being investigated as alternative energy conversion cycle. However, an accidental scenario must be evaluated, since a leakage inside the CO2-sodium heat exchanger would cause a reactive underexpanded CO2-into-Sodium jet, which in turn could lead to mechanical and thermal problems. A two-fluid approach has been investigated for the modelling of the two-phase jet. According to available flow maps, mist flow has been assumed at the leak exit, where high gas volume fraction and high interfacial slip velocity exist, and bubbly flow has been assumed for lower gas volume fraction and slip velocity. An interfacial friction model has been developed. Droplet and bubble diameters have been estimated following literature experimental results and using critical Weber number. For the drag coefficients, consistent correlations have been developed. A two-phase mixture turbulence model has been added. The interfacial friction approach has been implemented into the two-fluid model of the CFD software Ansys Fluent 14.0. Experimental gas-into-water tests have been realized in order to obtain visual information and to perform void fraction measurements through optical probe: numerical results are consistent with experimental ones in terms of void fraction profile during the injection transient and axial and radial void fraction profile at steady-state conditions. The two-fluid approach presented here will be the base for the implementation of a chemical reaction model, in order to account for the exothermic chemical reaction between the CO2 and the sodium.
- Published
- 2013
14. Two-fluid numerical approach for underexpanded gas-into-liquid-sodium jets
- Author
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Vivaldi, Daniele, Gruy, Frédéric, Simon, Nicole, Lillouch, Fatima, Département Technologie Nucléaire (DTN), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Laboratoire des Procédés en Milieux Granulaires (LPMG-EMSE), École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-Centre National de la Recherche Scientifique (CNRS), Centre Sciences des Processus Industriels et Naturels (SPIN-ENSMSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT), Département PROcédés Poudres, Interfaces, Cristallisation et Ecoulements (PROPICE-ENSMSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SPIN, and CEA Cadarache Departement des Techniques Nucleaires LEIPC
- Subjects
[SPI.GPROC] Engineering Sciences [physics]/Chemical and Process Engineering ,Two-fluid numerical ,gas-into-liquid-sodium jets ,[SPI.GPROC]Engineering Sciences [physics]/Chemical and Process Engineering - Abstract
International audience; Pas de résumé
- Published
- 2012
15. A numerical model for the CO2-sodium chemical interactions in Sodium Fast nuclear Reactors.
- Author
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Vivaldi, Daniele, Gruy, Frédéric, and Perrais, Christophe
- Subjects
- *
SUPERCRITICAL carbon dioxide , *SODIUM compounds , *NUCLEAR reactors , *BRAYTON cycle , *EXOTHERMIC reactions - Abstract
Supercritical CO2 (sCO2) Brayton cycles have gained interest in the frame of Sodium-cooled nuclear Fast Reactors (SFRs), as an alternative to the conventional water Rankine cycles. If CO2 leaks inside the CO2-Na heat exchanger, an underexpanded CO2-into-liquid-sodium jet is formed. CO2 chemically reacts with sodium, following an exothermic reaction which forms mainly solid products. In order to develop a model to numerically reproduce the jet development, a detailed description of the CO2-Na chemical reaction mechanism must be investigated. In this paper, a chemical reaction model at the dispersed phase scale between CO2-sodium, inside an underexpanded CO2-into-sodium jet, is presented. The model considers the reaction between a sodium droplet with the surrounding CO2 environment for the region close to the leakage, where mist flow is supposed to exist, and between a CO2 bubble with the surrounding liquid sodium environment for the region further downstream the leakage, where bubbly flow takes place. The depletion rate for a single particle (droplet or bubble) is determined, as a function of the main influencing parameters, such as temperature, droplet slip velocity, bulk mass fractions, and the chemical kinetics. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
16. Modelling of a CO2-gas jet into liquid-sodium following a heat exchanger leakage scenario in Sodium Fast Reactors.
- Author
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Vivaldi, Daniele, Gruy, Frédéric, Simon, Nicole, and Perrais, Christophe
- Subjects
- *
CARBON dioxide , *GASES , *JETS (Nuclear physics) , *SODIUM , *HEAT exchangers , *FAST reactors , *SODIUM cooled reactors - Abstract
Sodium-cooled Fast Reactors (SFRs) represent one of the most promising technologies in the context of generation IV nuclear power reactors. In order to avoid a reaction between sodium and water when Rankine cycles are employed, the concept of Brayton cycles using supercritical CO2 (SCCBCs) is being investigated as alternative energy conversion cycle. However, an accidental scenario must be evaluated, since a leakage inside the CO2-sodium heat exchanger would cause a reactive underexpanded CO2-into-sodium jet, which in turn could lead to mechanical and thermal problems. A two-fluid approach has been investigated for the modelling of the two-phase jet: according to flow maps, mist flow has been assumed at the leak exit, where high gas volume fraction and high interfacial slip velocity exist, and bubbly flow has been assumed for lower gas volume fraction and slip velocity. An interfacial friction model has been developed. Droplet and bubble diameters have been estimated following literature experimental results and using critical Weber number. For the drag coefficients, consistent correlations have been developed. A two-phase mixture turbulence model has been added. The interfacial friction approach has been implemented into the two-fluid model of the CFD software Ansys Fluent 14.0.3D numerical simulations of gas-into-water jets have been performed for vertical upward jets and optical probe technique has been employed for the experimental measurement of void fraction inside an underexpanded N2-into-water jet: numerical results agree with experimental results in terms of axial and radial void fraction profile. The two-fluid approach presented here will be the base for the implementation of a chemical reaction model, in order to account for the exothermic chemical reaction between the CO2 and the sodium. [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
- View/download PDF
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